1) Field of the Invention
The present invention relates to a technique of detecting a moving body by conducting various processing on an image picked up.
2) Description of the Related Art
As one of various conventional crime-prevention systems, there has been known a technique in which a moving body detecting apparatus detects a break-in body through the use of an image to make notification on the basis of the detection results. In general, this moving body detecting apparatus previously stores an image including no moving body as a background image and calculates a difference between the an image newly picked up and the previously stored background image for recognition of a moving body. Concretely, a difference between an image picked up and a background image is obtained to conducting threshold processing on a difference value for each pixel for producing a binary image so that a moving body is extracted through noise removal and labeling processing on the binary image. Moreover, a feature quantity of the moving body is calculated to make a decision as to whether or not the calculated feature quantity agrees with a predetermined judgmental criterion for making a decision as to whether that moving body is to be notified or not. In this case, the “feature quantity” signifies a physical quantity characterizing a moving body and, for example, there are “existence time” for which a moving body exists in an image, “area” of the moving body, “vertical and horizontal dimensions” of the moving body, “moving speed” at which the moving body moves, and others.
Meanwhile, in a case in which a moving body detecting apparatus is used as an approach detecting apparatus for a vehicle, a shadow of a moving body, together with the moving body, can appear at a window portion of the vehicle due to sunlight. For this reason, some moving body detecting apparatuses involves a technique of eliminating a shadow of a moving body from a picked-up image for precise detection of the moving body (for example, see Japanese Patent Laid-Open No. HEI 07-220049). Concretely, a difference between a background image and a background shifted image obtained by shifting the background image by a predetermined number of pixels horizontally and vertically is calculated to produce a background difference image which in turn, is binary-processed to produce a background binary image. moreover, as with the background image, with respect to a picked-up image obtained by taking a pickup (photograph) of a moving body, a pickup difference image is produced on the basis of a difference between a pickup image and a pickup shifted image obtained by shifting the pickup image by a predetermined number of pixels vertically and horizontally and the pickup difference image is binary-processed to produce a pickup binary image. Still moreover, the background binary image and the pickup binary image are exclusive-OR-processed to an exclusive-OR image, and the exclusive-OR image and the background binary image are AND-processed to remove the shadow of the moving body.
In addition, as shown in FIG. 29, a passer or bicycle passing by a vehicle can be reflected in a window portion of the vehicle (see “803” in the illustration). FIG. 29 shows an image obtained by photographing a window portion (see “801” in the illustration) and a door portion (see “802” in the illustration) near a rear seat from its interior side. Still additionally, a shadow of a building due to sunlight, a reflection of head light of a vehicle in the nighttime, a shadow of a tree or the like can be reflected in the interior of a vehicle (see “804” in the illustration). For this reason, in some moving body detecting apparatuses, the aforesaid judgmental criterion is corrected on the basis of a feature quantity of each of things most extracted as moving bodies from a pickup image in the past (for example, Japanese Paten Laid-Open No. HEI 11-203567. For example, in the case of the aforesaid “area”, if the judgmental criterion is set to be “area=10000 pixels (central value)±1000 pixels (width)”, when moving bodies whose areas are 8000 pixels to 10000 pixels are most extracted therefrom, the aforesaid judgmental criterion is corrected to “area=9000 pixels (central value)±1000 pixels (width)”. Incidentally, likewise, the correction is made with respect to the other judgmental criteria such as “existence time”.
However, even if, as mentioned above, the shadow of a moving body is removed or the judgmental criterion is corrected on the basis of a feature quantity of a moving body, there is a possibility that the detected feature quantity of a moving body, such as a passer or shadow of a building, agrees with a judgmental criterion. In this case, the aforesaid moving body detecting apparatus is at risk of detecting that moving body as a body to be notified in error. Moreover, in a case in which the aforesaid judgmental criterion is set in advance or through correction on the basis of a feature of the whole body of a thief, for example, when only the upper half of the body or arm of the thief is reflected in a window portion of a vehicle, there is a possibility that the feature quantity of that thief can disagree with the aforesaid judgmental criterion and, in this case, the moving body detecting apparatus cannot detect the thief as a body to be notified. It can be considered that this applies likewise to moving body detecting apparatuses designed to detect a body to be notified on the basis of a feature quantity of a moving body. That is, for example, in the case of preventing a person committing a theft (which will be referred to hereinafter as a “thief” from breaking in the interior of a vehicle, both a passer and the thief are a human being and, hence, the feature quantities thereof becomes similar to each other. This is because the feature of the passer agrees with the judgmental criterion set for the purpose of detecting the thief.
Furthermore, the employment of such a moving body detecting apparatus is not limited to vehicles but being also applicable to a spot such as an entrance or window of a building requiring the prevention of the break-in of a thief or a place such as a store or art museum requiring the prevention of approach of a thief around an article or picture.